Metrohm 896 Professional Detector – Amperometry - Manual (Page 42)

6.3 General remarks regarding sensitivity fluctuations
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2.896.0020 896 Professional Detector – Amperometry
6.3 General remarks regarding sensitivity fluctuations
Sensitivity fluctuations of up to 20% per week are normal for an
unchanged system in constant operation.
The sensitivity can increase to approximately twice as much for a short
time when new working electrodes are inserted or when the conditions
change.
6.4 Problems with sensitivity
Problem Cause Remedy
Declining sensitivity. Measuring cell – Auxiliary
electrode contaminated. Clean the auxiliary electrode (see measuring
cell manual).
Incorrect eluent in the ref-
erence chamber. Remove purge stopper on the measuring cell,
wait until approx. 1 mL of eluent has emerged,
screw the purge stopper back in tightly.
Sample concentration is no
longer correct. Replace sample and/or standard solution.
Temperature fluctuations. ￭ Amperometric detector – Use preheating
capillary.
￭ IC instruments – Use column oven.
Replace the measuring cell. ￭ Use a measuring cell of the same type.
￭ Use the same spacer.
￭ Use the same electrodes.
Software – Measurement
potential incorrect. Optimize the measurement potential.
Measuring cell – Working
electrode contaminated. Clean the working electrode (see the leaflet for
the working electrode).
IC system – Eluent conta-
minated. Apply new eluent.
IC system – pH of the elu-
ent has changed. Check the pH of the eluent and optimize it if
necessary.